The purpose of the patient acquisition core is to create a patient data base for recruitment of study subjects for the program project. All projects of the Program Project, with the exception of the chemical synthesis project (Project 4), will require patient material for study. This core will take advantage of the existing clinical research center at Boston University to recruit subjects for study utilizing the demographic database and the established patient pool. The specific aims of this core are to: 1. Recruit, categorize (diagnose), and collect basic demographic and clinical data from periodontitis patients. 2. After obtaining informed consent, to collect appropriate blood and gingival crevicular fluid samples as required by the respective projects of the Program Project. 3. Attend to the treatments needs of the recruited subjects, with the intention of collecting post-treatment samples for further analysis in the respective projects of the Program Project.